类似的机器也曾搭乘美国宇航局的航天飞机在太空中飞行，但无法进行时间足够长的测试来证明它们是否有效。
Similar machines have flown in space aboard NASA's shuttles, but they couldn't be tested for long enough to prove whether they were effective.
在过去的会议中，常听到批评宇航局是平价太空旅行的障碍，今年却鲜有所闻。
It was typical in the past to hear much bashing of the space agency as a barrier to affordable space access at this meeting, but there was very little of it this year.
美国宇航局发布了哈勃太空望远镜拍摄的图像，显示了冥王星表面不寻常和多彩变化。
Nasa released images taken by the Hubble Space Telescope which revealed some unusual and colourful changes to the surface of Pluto.
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